Antennas are widely used to transmit and receive a variety of signals. For example, antennas are prevalent in radio frequency (RF) communications systems. To be effective, the antenna must be capable of transmitting or receiving RF energy from an outside environment. In an application, such as an antenna mounted external to a submarine, the aperture must provide protection from the outside environment, including pressures encountered at submarine ocean depths.
Until now, antennas on submarines have been designed as retractable tow assemblies that are stored in pressurized housing structures and deployed from the submarine for transmission or as mast mounted pressure compliant domed radomes. The deployable antenna has two significant limitations. First, time is required before transmission may begin to allow for the antenna to be physically deployed. Second, problems may arise with the mechanical deployment system of the antenna, leading to antenna failure or degradation. The domed radome has the disadvantage that in order to survive the pressure environment, the radome wall thickness must be substantial, which severely degrades RF signal propagation
A need exists to place an antenna aperture upon a submarine mast in order to provide for communications via the antenna to and from the submarine without the deployment of an antenna tow assembly and without the high RF signal loss resulting from radomes. The antenna aperture must allow for RF transmissions from a submarine antenna, as well as provide a barrier against the outside environment, including hydrostatic forces for the antenna electronics. The antenna aperture should preferably be mast mounted.
To provide an aperture for the isolation of antenna electronics external to the submarine, an antenna aperture must be designed and tested to meet hydrostatic pressure cycling to ensure acceptable performance on a submarine.
An antenna aperture that meets these needs would require both a high strength structural member and a wide angle impedance matching (WAIM) radome cover. The WAIM cover must meet both RF requirements and environmental requirements including hydrostatic pressure requirements.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings that illustrate, by way of example, the principles of the invention.